Lead bismuthate

The bismuth and oxygen atoms form negatively charged layers by creating repeating octahedral geometries.

[4] Due to this, lead bismuthate can be used in spectral devices, such as optical switches and photoionic devices, detection systems based on sensitivity to infrared (IR) and heat radiation, laser materials, optical waveguides, and crystal free fiber drawings.

As lead bismuthate melts in the glass forming process, it becomes less stable and tends to crystallize as the temperature decreases, creating a less translucent and glossy product.

Thus the lead bismuthate in conjunction with increasing concentrations of metal cation or oxide adducts such as Fe2O3, MnO or Gd2O3 increases the stabilization effect and transmission window of the lead bismuthate resulting in the crystallization of the glass structure.

[3] Researchers are working to improve lead bismuthate by expanding the transmitting window to fit even more optical applications.

Hence, both of them should be available and utilized together to minimize the crystallization and improve the glass stabilization so that there is only a slight decrease is the infrared transmission.

Lead bismuthate forms a pentavalent structure. [ 1 ] Six oxygen atoms are coordinated octahedrally to each bismuth atom. Through the edge-sharing of oxygen atoms, a Bi 2 O 6 2− layer is formed. Positively charged lead atoms are dispersed between the layers, forming a hexagonal unit cell, with a lead atom in each of the corners.
Lead bismuthate has a broad transmittance range in the IR spectra.7 When doped with Li 2 O to form Li 2 O-[Bi 2 O 3 -PbO], the transmittance can increase beyond 10-15 micrometers. The figure above shows the IR spectra of 30Li2O-35[Bi2O3-PbO] glass composition, which contains 30 mole percent Li 2 O. [ 3 ]
Infusing varying mole concentrations of Li2O within the structure of lead bismuthate to form Li 2 O-[Bi 2 O 3 -PbO] can increase the transmittance spectra of lead bismuthate glass within and beyond the visible range.7 The figure shows the UV-Vis spectra of lead bismuthate glass compositions with (a) 20, (b) 30, (c) 40, (d) 50 and (e) 60 mole percent of Li 2 O. [ 3 ]